The present invention relates to an electronic endoscope system including an electronic endoscope and a video processor connected to the electronic endoscope.
Conventionally, the electronic endoscope includes a solid-state image pickup device, such as a CCD (Charge Coupled Device), to capture an image of an affected part or the like. The electronic endoscope further includes a driving circuit for driving the solid-state image pickup device. Since the driving circuit must be substantially matched with characteristics of the solid-state image pickup device, each electronic endoscope includes a driving circuit that is adjusted for the image pickup device provided in that electronic endoscope.
The video processor which is connected with the electronic endoscope sends clock pulses required for generating driving signals in the driving circuit of the electronic endoscope. However, the clock pulses must have a relatively high frequency (e.g., 8 MHz) which may constitute a noise source. The noise generated may not be reduced by grounding because, in order to protect a patient, circuits in a medical instrument, such as the electronic endoscope system, cannot be grounded.
When noise is produced, the noise forms a capacitive coupling with ground or with ungrounded metal components, and the like, and the noise may radiate outside of the electronic endoscope or out of a cable connecting the electronic endoscope with peripheral equipment. In such a case, the cable may function as an antenna, producing an adverse influence on images displayed using the electronic endoscope system itself, and/or cause malfunctions.